Wednesday is the day when energy levels plummet, work stress is at a peak and the effects of any weekend late nights finally kick in.
The research found one in ten women (12 per cent) find Wednesday the most stressful day in a typical week.
But Thursday is the day they are most likely to romance which could contribute to why women feel so happy on a Friday - 60 per cent name it as their happiest day, the 'Daily Mail' reported.
A quarter of women feel stressed several times a week - while one in five (19 per cent) admit they will work through Wednesday's lunch hour.
The study, carried out by tanning brand, St Tropez found two thirds experience a 'slump in energy levels' mid-afternoon every Wednesday.
This forces a quarter of women to reach for a sugary snack on a bid to boost their mood and energy.
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"It's fascinating that 3.30 pm on a Wednesday is the time women look their oldest. Combine the highest stress levels of the week on a Wednesday with the natural mid-afternoon slump and it seems that's why women can look older than their years," Nichola Joss, St Tropez skin expert, said.
Almost half of women (46 per cent) are likely to indulge in a boozy treat at the weekend - another reason why women look their eldest mid-week.
Joss said it can take a few days for the signs of the boozy weekend to show.
"Processing the toxins in alcohol and sugar can put strain on the body. It can take up to 72 hours for the visible effects of alcohol to show, so the effects of drinking on the weekend may not present themselves until Wednesday afternoon," she added.
The shock of going back to work was shown to give many women sleepless nights.
More than a third (37 per cent) reported Monday night is when they are most likely to get a bad night's sleep.
"A lack of sleep on a Monday does not bode well for how the skin will look on Wednesday. The effects of a lack of sleep can take 48 hours to show on the face, so if many women sleep badly on Monday they will look their oldest on Wednesday," Joss said.
Another effect of the mid-week slump is that more than one in ten (12 per cent) women will abandon their skin care regime on a Wednesday.